This sample size ensures a power of 90% to detect differences in the fasting glycemia of at least 8mg/dL (0.44mmol/L), with a standard deviation (SD) of 20mg/dL. (1.1mmol/L) or a difference of 14mg/dL (0.77mmol/L) in the 2 hours post load glycemia SD of 40mg/dl (2.2mmol/L).